U.S. patent number 4,065,149 [Application Number 05/689,302] was granted by the patent office on 1977-12-27 for anti-jackknife apparatus.
This patent grant is currently assigned to Safe Track Manufacturing Limited. Invention is credited to Bernard E. Roth.
United States Patent |
4,065,149 |
Roth |
December 27, 1977 |
Anti-jackknife apparatus
Abstract
The invention relates to an anti-jackknife apparatus for a
tractor-trailer having a fifth wheel on the tractor unit to which
the trailer is coupled. The fifth wheel is adapted to permit the
trailer to be coupled thereto so that the trailer can turn with
respect to the tractor unit when the tractor-trailer is in normal
use. Braking means are provided in association with the fifth wheel
and are adapted, when operated, to restrict turning of the trailer
with respect to the tractor unit in use. Control means for the
braking means are provided and are adapted to be operated from the
driving cab of the tractor unit whereby, in use, the braking means
can be used to arrest or prevent uncontrolled swinging of the
trailer with respect to the tractor unit.
Inventors: |
Roth; Bernard E. (Barrie,
CA) |
Assignee: |
Safe Track Manufacturing
Limited (Burlington, CA)
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Family
ID: |
25667734 |
Appl.
No.: |
05/689,302 |
Filed: |
May 24, 1976 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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626146 |
Oct 28, 1975 |
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Current U.S.
Class: |
280/432 |
Current CPC
Class: |
B62D
53/0878 (20130101) |
Current International
Class: |
B62D
53/00 (20060101); B62D 53/08 (20060101); B62D
053/10 () |
Field of
Search: |
;280/432,474,438A
;188/16P |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodman; Philip
Assistant Examiner: Schrecengost; R.
Attorney, Agent or Firm: Rogers, Bereskin & Parr
Parent Case Text
This application is a Continuation-in-part of application Ser. No.
626,146 filed Oct. 28, 1975 and now abandoned.
Claims
What I claim is:
1. A tractor unit having an anti-jackknife apparatus and
including:
a fifth wheel formed with a slot to receive a coupling pin on a
trailer to be coupled to the tractor unit;
bearing means disposed between the fifth wheel and the tractor unit
and adapted to permit the fifth wheel to turn with respect to the
tractor unit about an upright axis;
means for preventing a trailer coupled to the tractor unit from
turning with respect to the fifth wheel, the trailer and fifth
wheel turning together about said axis when the tractor unit is
coupled to a trailer and is negotiating a turn in use;
braking means associated with the fifth wheel and including at
least one fluid pressure operated actuator adapted to be coupled to
a source of fluid pressure independent of the normal road wheel
braking circuit of the tractor unit, said braking means being
arranged, when operated, to restrict turning of the fifth wheel
about said axis and thereby to arrest or prevent uncontrolled
swinging of the trailer with respect to the tractor unit; and,
control means for said braking means, said control means
including:
a first variable pressure valve which has an input connected
directly to said source of fluid pressure, and an output, and which
is operable manually under the control of a driver of said tractor
unit in use to vary the fluid pressure at said output of the
valve;
a second variable pressure valve disposed in parallel with said
first variable pressure valve and having an input connected
directly to said source of fluid pressure, and an output, and which
is coupled to a foot brake of the tractor unit so that the valve is
operated in response to operation of the foot brake to vary the
fluid pressure at said output of the valve; and,
a selector valve which has an output coupled to said actuator of
the braking means, first and second inputs coupled respectively to
the outputs of said first and second variable pressure valve, and a
valve member which is movable between a first position in which the
first input of the selector valve is coupled to said output so that
the braking means are controlled exclusively by said first variable
pressure valve under the control of a driver of the tractor unit,
and a second position in which said second input of the selector
valve is coupled to said output and said braking means is operated
exclusively by said second variable pressure valve under the
control of the foot brake of the tractor unit.
2. A tractor unit as claimed in claim 1, further comprising a brake
drum associated with said fifth wheel so as to turn with the fifth
wheel in use, wherein the braking means are adapted to frictionally
engage a curved surface of the said brake drum to restrict turning
of the fifth wheel in use.
3. A tractor unit as claimed in claim 2, wherein the brake drum is
mounted below the fifth wheel and is disposed co-axially with
respect to the said axis of turning of the fifth wheel, and wherein
the apparatus further includes a base plate mounted on the tractor
unit and adapted to support the brake drum and hence the fifth
wheel, the said bearing means being mounted on the base plate and
being coupled to the brake drum, and the said braking means being
carried by the base plate for action on the brake drum.
4. A tractor unit as claimed in claim 3, wherein the said braking
means comprises an expanding shoe braking mechanism disposed on the
said base plate inside the brake drum and including at least one
shoe positioned to act on the inner curved surface of the brake
drum, whereby movement of the said shoe into engagement with the
said surface of the drum applies a braking force to the fifth
wheel.
5. A tractor unit having an anti-jackknife apparatus and including
a fifth wheel formed with a slot to receive a coupling pin on a
trailer to be coupled to the tractor unit, wherein said
anti-jackknife apparatus comprises:
bearing means disposed between the fifth wheel and the tractor unit
and adapted to permit the fifth wheel to turn with respect to the
tractor unit about an upright axis;
means for locking a trailer coupled to the fifth wheel against
turning movement with respect to said fifth wheel, said locking
means being disposed below the fifth wheel and comprising:
at least one locking pin arranged adjacent said slot in the fifth
wheel, the fifth wheel being apertured at the position of the pin
and the pin being movable between an inoperative position in which
it is retracted below the surface of the fifth wheel, and an
operative position in which the pin projects above such surface for
engagement in a complimentary aperture in the underside of a
trailer coupled to the fifth wheel in use; means for moving the
locking pin between said operative and inoperative positions; and
means for retaining the locking pin in said operative position to
lock a trailer coupled to the fifth wheel against turning movement
with respect to the latter, whereby the trailer and the fifth wheel
turn together about said axis when the tractor unit is coupled to a
trailer and is negotiating a turn in use;
in association with the fifth wheel, braking means including at
least one actuator adapted to be coupled to a source of fluid
pressure, said braking means being adapted, when operated, to
restrict turning of the fifth wheel about said axis and thereby
arrest or prevent uncontrolled swinging of the trailer with respect
to the tractor unit; and,
control means for varying the pressure of said fluid, said control
means including a first variable pressure valve which is operable
manually under the control of the driver; a second variable
pressure valve which is coupled to the foot-brake of the tractor
unit and which is operated in response to operation of the
foot-brake; and a selector valve which is coupled to said variable
pressure valves and which is adapted to be operated to select which
of said variable pressure valves controls said actuator.
Description
This invention relates to an anti-jackknife apparatus for a
tractor-trailer having a so-called "fifth wheel" on the tractor
unit to which the trailer is coupled.
The fifth wheel provides a free pivot about which the trailer can
turn relative to the tractor unit, for example, when making turns
or when parking. Due to the fact that movement of the trailer about
the pivot is unrestricted, however, a trailer may "jackknife" when
braking under slipperly road conditions, for example. When this
happens, the trailer swings uncontrollably about the pivot provided
by the fifth wheel. Frequently, this results in an accident. Also,
a trailer may tend to "fishtail" (that is, oscillate about the
fifth wheel pivot) on a highway due to cross-winds.
Examples of prior art anti-jackknife devices are disclosed in
Canadian Pat. Nos.: 904,373; 815,414; 802,073; 797,701; and
546,504.
An object of the present invention is to provided an improved
apparatus which is operable by the driver of a tractor-trailer and
which allows him to arrest or prevent uncontrolled swinging of the
trailer about the fifth wheel pivot.
According to one aspect of the invention, the apparatus includes a
fifth wheel which is adapted to be mounted on the trailer unit and
is adapted to permit the trailer to be coupled thereto so that the
trailer can turn with respect to the tractor unit when the
tractor-trailer is in normal use. Braking means are provided in
association with the fifth wheel and are adapted, when operated, to
restrict turning of the trailer with respect to the tractor unit in
use. Control means for the braking means are provided and are
adapted to be operated from the driving cab of the tractor unit
whereby, in use the braking means can be used to arrest or prevent
uncontrolled swinging of the trailer with respect to the tractor
unit.
The invention will be better understood by reference to the
accompanying drawings, in which:
FIG. 1 is a perspective view of a tractor-trailer having an
anti-jackknife apparatus according to the invention, the trailer
being shown uncoupled from the tractor unit;
FIG. 2 is an exploded perspective view of the fifth wheel coupling
of the tractor unit;
FIG. 3 is a vertical sectional view on line 3--3 of FIG. 2, the
coupling being shown in the assembled condition;
FIG. 4 is a plan view of the fifth wheel, partly broken away to
show the mechanism for locking the trailer coupling pin to the
fifth wheel, the pin being shown in a position prior to full
engagement with the fifth wheel;
FIG. 5 is a view similar to FIG. 4 showing the coupling pin fully
engaged with the fifth wheel;
FIG. 6 is a diagrammatic illustration of the control for the
anti-jackknife apparatus;
FIGS. 7, 8 and 9 are plan views of different fifth wheel
construction according to three alternative embodiments of the
invention; FIGS. 8 and 9 being on a somewhat smaller scale than
FIG. 7;
FIGS. 10 and 11 are exploded perspective views similar to FIG. 2
illustrating two further embodiments of the invention;
FIG. 12 is a perspective view of a fifth wheel according to another
embodiment; and,
FIG. 13 is a perspective view of an adaptor block for fitment to a
coupling pin on a conventional trailer;
FIG. 14 is a perspective view, partly broken away, of a fifth wheel
assembly according to a further feature of the invention;
FIG. 15 is a partly sectioned side view corresponding to FIG. 14;
and,
FIG. 16 is a detailed sectional view on line 16--16 of FIG. 15.
Reference will first be made to FIG. 1 which shows a
tractor-trailer including a tractor unit 20 and a trailer 22. A
fifth wheel coupling 24 is provided on the frame 26 of the trailer
unit. As is conventional, the trailer 22 has at its forward end a
depending coupling pin which is releasably connected to the fifth
wheel coupling 24 and by which the trailer 22 is connected to the
tractor unit 20. The coupling pin is not visible in FIG. 1 but is
shown separate from the trailer at 28 in FIG. 2.
In FIG. 2, two parallel outer channel members of the frame 26 of
the tractor unit 20 are visible at 30. The fifth wheel coupling 24
is mounted between these members 30. The coupling includes a fifth
wheel 32 which is of plate form and which includes a part circular
portion 34 and a pair of projections 36 having upper surfaces which
slope downwardly from the portion 34. The projections 36 are spaced
from one another to define an entrance to a slot 38 formed in the
part circular portion 34. As can be seen, the slot 38 is disposed
on a line which extends diametrically with respect to the part
circular portion 34 and which is disposed mid-way between the two
projections 36. The pin 28 is formed with a pair of flats 39 and
the slot is dimensioned to snugly receive the coupling pin 28 so
that the pin (and hence the trailer) is coupled to the fifth wheel
and cannot turn relatively thereto. A flange 40 extends around the
lower end of the pin 28 and is disposed below the part circular
portion 34 of the fifth wheel when the pin is fully engaged in the
slot 38. A locking mechanism, part of which is visible in FIG. 2
below the slot 38 is provided to retain the pin 28 in its fully
engaged position in the slot and will be described later with
reference to FIGS. 3 and 5.
The construction of the fifth wheel 32 as so far described is
generally conventional. Assuming the tractor unit and trailer are
initially separate with the trailer parked on stands 41 (FIG. 1),
they are coupled together by backing the tractor unit up to the
trailer so that the pin enters the space between the two
projections 36 on the fifth wheel. Continued movement of the
tractor unit towards the trailer causes the pin to enter the slot
38 and move back to the fully engaged position. The sloping upper
surfaces of the projections 36 serve to lift the trailer slightly
off its stands as the pin 28 enters the slot 38, the undersurface
of the trailer sliding up the said surfaces of the projections.
Engagement of the pin 28 with the fifth wheel is further assisted
by the fact that the fifth wheel coupling 24 is pivotable about a
horizontal axis which is denoted X-X in FIG. 2 and which is
disposed at right angles with respect to the channel members 30 of
the tractor unit frame. Due to the projections 36, the balance of
the fifth wheel is such that it tends to naturally tip downwardly
at its outer end (the end having the projection 36) so that the
projections will always pass below the trailer as the tractor unit
is backed up.
The fifth wheel 32 is supported on the members 30 through the
intermediary of a circular base plate 42. A pair of bearing blocks
are bolted to the upper flanges of the channel members 30 in
transversely aligned positions and are adapted to turnably receive
a pivot shaft 46 which is frictionally engaged in a corresponding
pair of apertured formations 48 which depend from the underside of
plate 42. The fifth wheel 32 is also turnably mounted on the base
plate 42 by way of a tapered shaft 50 which projects upwardly from
the centre of plate 42. The axis of turning is denoted Y-Y. The
inner races of a pair of roller bearings 52, 54 are fitted to the
shaft 50 (see FIG. 3) and the outer races of the bearings are
carried in a housing 56 which is coupled to the fifth wheel 32 as
will be described. Housing 56 is disposed at the centre of a
circular plate 58 positioned below and parallel to the part
circular portion 34 of the fifth wheel. A cylindrical member 60
extends around the periphery of plate 58 and its lower margin
surrounds the outer edge of the base plate 42, as can be seen from
FIG. 3. The part circular portion 34 of the fifth wheel 32 has a
depending skirt 62 which is coupled to the upper margin of the
cylindrical member 60 by bolts 64 (FIG. 3).
Mounted on the upper surface of plate 42 are a pair of brake shoes
66 which are curved to conform to the curvature of the inner
surface of the cylindrical member 60 described above. It will be
appreciated that this member and the plate 58 in effect define a
brake drum, on the inner surface of which the brake shoes 66 act.
Each shoe 66 includes an outer layer 68 of a friction material
which makes contact with the inner surface of the cylindrical
member 60. The brake shoes 66 are coupled to the base plate 42 by
coil springs 70 as is conventional in vehicle brakes and are drawn
together by a pair of tension springs 72. A pair of double acting
actuators 74 are fitted to the base plate 42 between the ends of
the respective brake shoes 66 and are adapted to be operated to
move the shoes 66 outwardly into frictional engagement with the
inner surface of the member 60. The method of operating the
actuactors 74 will be described later in relation to FIG. 6. It is
sufficient to note here that the actuactors can be progressively
operated from the cab of the tractor unit of the tractor-trailer
combination to apply any appropriate degree of braking effort to
the inner surface of the member 60 and hence to the fifth wheel.
Accordingly, when the trailer 22 is coupled to the tractor unit 20,
a braking effort can be applied to the fifth wheel to either lock
the trailer with respect to the tractor unit or to provide any
required degree of restraint on turning movement of the trailer
with respect to the tractor unit.
Referring now to FIGS. 4 and 5, the locking mechanism for retaining
the coupling pin 28 on the trailer in the slots 38 in the fifth
wheel is generally denoted 76 and is mounted on the underside of
the part circular portion 34 of the fifth wheel 32. The mechanism
includes a first element 78 against which the coupling pin 28 abuts
as it moves towards the end of slot 38 and which is formed with a
recess 80 to receive the flange 40 on the coupling pin 28. Element
78 is carried by a short rod 82 fitted with a compression spring 84
which biasses the element 78 towards the open end of slot 38. A
rack 86 is formed in one side of element 78 and is engaged by
complementary teeth 88 forming a pinion section on a second element
90 which is pivoted to the underside of the fifth wheel at 92. Due
to the rack and pinion connection between element 78 and element
90, the latter is automatically turned about its pivot 92 to engage
behind the flange 40 on the pin 28 as the pin moves to its end
position in slot 38. FIG. 4 shows the positions of the locking
elements as pin 28 begins to move along the slot 38 in the
direction of arrow 96 as the tractor unit of the tractor-trailer is
backed up to the trailer. FIG. 5 shows the positions of the
elements 78 and 90 when element 90 has engaged behind the pin 28.
Element 90 is held in this position by a stop 98 which engages
behind a shoulder 100 on element 90. The stop 98 is slidably
mounted in an aperture in a support block 102 secured to the
underside of the fifth wheel. The inner end of element 98 is
coupled to a bellcrank lever 104 which projects beyond the
periphery of the fifth wheel. Element 98 is biassed into the
locking position in which it is shown in FIG. 5 by a compression
spring 106 mounted on a pin 108 coupled to element 98. Spring 106
acts between the rear end of element 98 and a stop 110 on the
underside of the fifth wheel.
The locking mechanism 76 can be released when the trailer 22 is to
be uncoupled from the tractor unit 20 by moving lever 104 in the
direction of arrow 112 in FIG. 5, which causes the stop element 98
to withdraw in the direction of arrow 114. If the tractor unit is
then driven away from the trailer, pin 28 will tend to move out of
slot 38 and will cause lock element 90 to return to the position in
which it is shown in FIG. 4.
Reference will now be made to FIG. 6 in describing how the braking
means incorporated in the fifth wheel coupling is operated. The
trailer is indicated diagrammatically at 22 in FIG. 6 and the
tractor unit at 20. The actuactors 74 are pneumatically operated
and are coupled to a common supply line 116 which is connectible by
way of a number of valves (to be described) with the pneumatic
supply conventionally provided on such tractor units. The supply is
indicated at 118. The first of these valves is a selector valve 120
which is connected in line 116 and is operable to connect the
actuators 74 selectively to one of two spool valves 122 and 124.
Valve 122 is a manually operable valve having an operating lever
126 which can be moved by the driver of the tractor unit to vary
the pressure of the air supplied to the actuactors 74 from the
supply 118 to control the force with which the fifth wheel brake is
applied. The other valve 124 is coupled with the brake pedal of the
tractor unit parallel with the conventional master cylinder so that
valve 124 is operated when the brake is applied and varies the
pressure of the air supplied to the actuactors 74 in accordance
with effort applied to the brake pedal.
Valve 120 is a conventional two-position spool valve having a body
128 in which a spool 130 is movable by an operating lever 132
between the position in which it is shown in FIG. 6, in which the
actuactors 74 are connected to valve 124, and the position
indicated in ghost outline in which the actuators are connected to
valve 122. Latching means (not shown) are provided to latch the
lever in either of its two positions. Valve 120 will be operated by
the driver of the tractor unit, depending on whether he wishes the
fifth wheel brake to be operated automatically in accordance with
the braking effort applied by the brake pedal of whether he wishes
to control the braking effect manually by means of lever 126.
Valve 122 includes a body 134 and a spool 136 formed with air
passageways 138. Spool 136 is biassed to one end of the body 134 by
a spring 140 and is coupled to the operating lever 126. Lever 126
may, for example, be mounted on the steering column of the tractor
unit so as to be readily accessible to the driver. Latching means
(not shown) are also provided in association with lever 120 so that
the driver can secure the lever in the "fully on" position if
necessary. Valve 124 is similar to valve 122 and primed reference
numerals have been used in referring to valve 124, to denote parts
which are similar to parts of valve 122. The spool 136' of valve
124 is coupled to the brake pedal 142 of the tractor unit by a
mechanical linkage indicated diagrammatically in FIG. 6.
In use, the driver of the tractor unit moves valve 120 to whichever
of its two positions he considers most appropriate. For example, if
the valve is in the position in which it is shown, braking force
will be applied to the fifth wheel whenever he operates the foot
brake of the tractor unit. Accordingly, when negotiating a curve,
for example, the driver may apply the tractor brakes and this will
both slow the tractor-trailer and will apply a restraint to the
fifth wheel pivot. Alternatively, if the driver moves the valve 120
to the other position, he can control the fifth wheel brake
completely independently of the tractor-trailer brakes. For
example, he might consider it desirable to apply a fairly light
restraining force to the fifth wheel pivot to prevent the trailer
"fish-trailing" (that is, swinging from side to side) on a highway.
In another situation, the driver might consider it advisable to
completely lock the fifth wheel pivot by moving the lever 126 to
its "fully on" position and locking it in that position.
Reference will now be made to FIGS. 7, 8 and 9 in describing
alternative embodiments of the invention.
Referring first to FIG. 7, the fifth wheel is generally denoted 144
in this view and differs from that shown in the previous embodiment
in that it is formed with two slots 146. Similarly, the trailer is
modified by the provision of two depending coupling pins 148
positioned to be received in the said slots. An appropriate locking
element indicated diagrammatically at 150 is provided in
association with each slot to retain the relevant pin therein. In
this case, the pins are both of circular shape in cross-section.
Flats on the pins are not necessary since the provision of two pins
makes it impossible for the trailer to turn with respect to the
fifth wheel. Further, the provision of two coupling pins halves the
load on each pin compared with the previous embodiment and
accordingly reduces the risk of failure of the coupling between the
tractor unit and the trailer.
The embodiment of FIG. 7 also differs from the previously described
embodiment in that an external band brake is used in association
with the fifth wheel in place of the expanding shoe type of brake
shown in FIG. 2. As in the FIG. 2 embodiment, the fifth wheel 144
has a depending skirt 152 which is bolted to a cylindrical member
154 similar to member 60 in FIGS. 2 and 3, which forms a brake
drum. A base plate 156 is pivotally coupled to the frame of the
tractor unit and carries bearings which allow the fifth wheel to
turn as in the previous embodiment. Base plate 156 also carries
single-acting pneumatic actuactor 156 which is connected to one end
of a metal band 158. The band extends around the exterior surface
of member 154 and its opposite end is anchored at 160 to the base
plate 154. Actuator 156 is coupled to the pneumatic supply of the
tractor unit as in the previous embodiment so that air can be
supplied to the actuactor to tighten the band 158 and restrain the
fifth wheel against turning movement.
Reference will now be made to FIG. 8 which shows a further
alternative embodiment of the invention. In this embodiment, the
fifth wheel is indicated at 162 and includes the part circular
portion 164 which has a series of teeth 166 around its periphery.
The frame of the tractor unit is indicated at 168 and carries a
pneumatic actuator 170 which is coupled to the pneumatic circuit of
the tractor. The actuator includes an operating rod 172 which
carries at its outer end a segment 174 provided with teeth
complementary to those around the periphery of the fifth wheel. The
fifth wheel is mounted in bearings which allow it to turn in the
same fashion as the previously described embodiments.
Operation of the actuactor 170 causes the segment 174 to be
projected towards the fifth wheel so that the teeth on the segment
engage in appropriate section of the teeth on the fifth wheel to
lock the fifth wheel in the angular position in which it is
disposed at that time. It will be appreciated that this form of
braking means does not allow for slip. Accordingly, the actuator
170 may be coupled to a simple on/off valve in the pneumatic supply
line. The valve may be operated manually by the driver of the
tractor unit.
FIG. 9 illustrates a further embodiment which is a modification of
that shown in FIG. 8. In this case, the fifth wheel is of similar
form to that shown in the previous embodiment in that it is
provided with teeth around its periphery. Primed reference numerals
have been used in FIG. 9 to denote parts which are similar to those
shown in FIG. 8. In this embodiment the teeth 166' on the fifth
wheel 162' mesh with a pinion 165 which is mounted in bearings on
the frame 168' of the tractor unit. Accordingly, the pinion 175
turns in response to turning of the fifth wheel 162'. A brake drum
176 is mounted on the under side of pinion 175 to turn therewith
and is provided with an internal expanding shoe brake mechanism
similar to that shown in FIGS. 2 and 3. The brake mechanism is
coupled to the pneumatic supply of the vehicle as in the first
embodiment. The brake shoes are mounted on a back plate which is
rigidly fixed to the frame 168' of the tractor unit. Accordingly,
operation of the brake restrains the pinion 175 and hence the fifth
wheel 162' against turning movement. In this embodiment the fifth
wheel is not pivotable with respect to the frame of the tractor
unit.
Reference will now be made to FIG. 10 which illustrates an
embodiment of the invention in which the braking means associated
with the fifth wheel takes the form of a clutch assembly. The fifth
wheel is denoted 178 and is of similar form to the fifth wheel
shown in FIG. 2. The clutch assembly is generally denoted 180 and
is positioned between the fifth wheel 178 and a base plate 182
which is coupled to the frame 184 of the tractor unit in similar
fashion to the base plate 42 in FIG. 2. Parts of the FIG. 10
embodiment which are similar to parts of FIG. 2 will not be
described in detail since their construction will be evident from
the above description.
A circular plate 186 is attached to the bottom of the fifth wheel
(in FIG. 10 the plate is shown spaced below the fifth wheel for
clarity of illustration). Plate 186 is carried by a vertical,
rotatable shaft indicated in dotted lines at 188. The shaft is
supported for rotation in an outer sleeve 190 fixed to the base
plate 182 by way of bronze bushes 192. A ball bearing race
generally indicated at 194 is provided at the lower end of shaft
188 to support the weight of the fifth wheel.
The clutch assembly 180 includes a sleeve form hub 196 which fits
around the sleeve 190 and is coupled thereto by a key 198. Hub 196
has an integral upper flange 200 of circular shape and if formed at
a position just below the flange with an annular series 202 of
vertical ribs which extend around the hub and, in effect, form a
series of teeth. Two annular metal clutch plates 204, 206 are
positioned around the teeth 202 and the centre aperture of each
plate is formed with a series of inwardly directed teeth which
engage with the teeth 202. Accordingly, the plates 204, 206 are
vertically slidable with respect to the hub 196 but are drivably
coupled thereto by the said teeth. A free floating annular plate
210 of a friction material is positioned between the two clutch
plates 204, 206. A similar plate 212 is positioned between the
upper clutch plate 204 and the flange 200 of the hub 196. Each of
these plates is provided with a peripheral series of vertical ribs
213 similar to the ribs on the clutch plates 204, 206 which in
effect define teeth around the periphery of each plate. These teeth
engage with a series of complementary teeth 214 on the inner
surface of an annular drum member 215 which depends from the plate
186. Accordingly, the friction plates 210, 212 turn with respect to
the clutch plates 204, 206 as the fifth wheel and hence the drum
member 215 turn. In this condition, the clutch is "off" and the
fifth wheel 178 is free to turn with the trailer to which it is
coupled. To move the clutch to the "on" position, the lower clutch
plate 206 is moved upwardly, sliding on the ribs 202 carried by the
hub 196. As it moves up, plate 206 pushes the lower friction plate
210 against the upper clutch plate 204. This plate in turn urges
the upper friction plate 212 against the upper flange 200 of the
drive hub. In other words, the "sandwich" of clutch plates and
friction plates are compressed, frictionally coupling the turnable
fifth wheel with the stationary centre sleeve 190. The force
applied to the lower clutch plate can be controlled to allow a
degree of slip between the friction plates and the clutch plates,
or the plates can be clamped firmly together to in effect lock the
fifth wheel.
Movement of the clutch plates is effected by an operating assembly
generally denoted 216 and including an operating fork 218 which is
disposed in a vertical plane below the base plate 182 and which
includes two arms 220 arranged to project upwardly through
apertures in the base plate. The fork is coupled to an actuactor
unit 222 attached to the underside of plate 182 by a bracket 223
and coupled to the hydraulic system of the tractor unit in the same
fashion as the actuactors described in the preceding embodiments.
The arms 220 are coupled by a collar 224 to a sleeve 226 which is
mounted concentrically with respect to the sleeve 190. Sleeve 226
is vertically slidable with respect to the sleeve 190 and is
provided with a tapered inner surface 228. This surface bears
against a series of balls 230 mounted in races 232, 234 which are
slidably fitted around the drive hub 196. The balls 230 are
slidable radially with respect to the drive hub 196. The upper race
232 bears against a flanged collar 236 which has an external screw
thread 238. An adjusting ring 240 is screwed onto thread 236 and
has an upper face which bears against the lower clutch plate
206.
Accordingly, when the actuactor 222 is operated, the fork 218 moves
the sleeve 226 upwardly. By virtue of its tapered inner surface
228, the sleeve 226 engages the balls 230 and moves them upwardly.
In turn, this movement displaces the upper race 232 and the collar
233. The adjusting ring 240 carried by the collar bears against the
clutch plate 206 to urge the clutch plates and friction discs
together as described previously. When the hydraulic fluid pressure
applied to the actuactor 222 is reduced, the force urging the said
plates together reduces and the plates can move down.
FIG. 11 illustrates a further embodiment of the invention in which
a disc brake assembly is fitted to the underside of a fifth wheel.
The fifth wheel is generally denoted 242 and is of similar form to
the fifth wheel shown in FIG. 2; it will not therefore be described
in detail. A disc 244 is fixed to the underside of the fifth wheel
assembly by an annular member 246 which is attached to a plate 248
at the underside of the fifth wheel and also to the disc 244. For
clarity of illustration, disc 244 is shown spaced below the fifth
wheel in FIG. 11. A base plate 250 is provided as in FIG. 2 and is
coupled to the frame 252 of the tractor unit, as in the FIG. 2
embodiment. Also as in that embodiment the base plate carries an
upstanding tapered shaft (not visible) which fits into a housing at
the underside of disc 244. Bearing races are provided in the
housing to allow the disc and fifth wheel to turn together with
respect to the base plate when the fifth wheel coupling is in the
assembled condition.
The base plate 250 carried two brake caliper assemblies 254
positioned at diametrically opposed positions. The calipers are
basically of the same construction as disc brake calipers used in
vehicle braking systems. Each caliper includes a housing 256 which
is shaped to define a slot 258 through which the disc passes. Each
caliper housing 256 is shaped to define two hydraulic cylinders,
positioned one above and one below the disc. The bases of the upper
cylinders are visible at 259 in FIG. 11. Each of these cylinders
receives a piston, not visible, which is movable towards the disc
by hydraulic fluid supplied to the caliper under pressure. Each
piston bears on a disc pad 260 of a friction material which lies in
surface contact with the relevant face of the disc 244. The
calipers 256 are coupled to the hydraulic system of the tractor
unit by pipes 261 as described in the first embodiment, whereby
fluid pressure can be applied to the calipers to urge the disc pads
against the discs to apply a restraining force tending to opposed
turning of the disc or to lock the disc against rotation.
Referring finally to FIG. 12, a fifth wheel similar to that shown
in FIG. 2 is generally denoted 262 and is fixed rigidly to the
frame 264 of a tractor unit. The fifth wheel 262 has a base plate
266 which carries four electromagnets 268 arranged with their axes
vertical. The core of each magnet is surrounded by a coil 270 (only
one of which is shown) and the coils are coupled to a generator
driven from the engine of the tractor unit. The coils are arranged
so that, when energized, two north poles and two south poles are
produced as indicated. An infinitely variable voltage control 272
is connected in the electrical supply to the coils 270 so that the
magnetic field intensity produced by the electromagnets 268 can be
varied. The voltage control 272 is positioned in the cab of the
tractor unit.
In FIG. 12, part of the leading end of the trailer is indicated in
ghost outline at 274. A plate 276 of a magnetic material is secured
to the underside of the leading end of the trailer and is fitted
with a depending coupling pin 278 of conventional form having a
circular cross-section. When the coupling pin 278 is received in a
slot in the fifth wheel, the plate 276 overlies the upper surface
of the fifth wheel. If the voltage control 272 is operated to
energize the electromagnets 268, 270, the plate 276 is drawn down
onto the upper surface of the fifth wheel and magnetically retained
thereon. By varying the magnetic field intensity produced by the
electromagnets 268, the force with which the plate 276 is drawn
down onto the fifth wheel can be adjusted to apply an appropriate
degree of restraint to turning of the trailer with respect to the
tractor unit. For example, if the control is operated to produce
maximum field intensity, the plate 276 will be locked to the fifth
wheel so that the trailer 274 will be unable to turn with respect
to the tractor unit. If the field intensity is reduced by
appropriate operation of the control unit 272, the retaining force
will be correspondingly reduced and the trailer will be able to
turn against a restraining force.
In a modification of the embodiment according to FIG. 12, the fifth
wheel 262 may be mounted to turn with respect to the frame 264 of
the tractor unit as in the FIG. 2 embodiment. The electromagnets
268 would then be mounted on a base plate carried by the tractor
unit and would be arranged to act either directly on the underside
of the fifth wheel itself or on a plate of a magnetic material
mounted below the fifth wheel. In this case, the coupling pin on
the trailer will be provided with flats so that the trailer and
fifth wheel cannot turn with respect to one another.
FIG. 13 shows a coupling block 280 which can be fitted to a
conventional round coupling pin 282 to in effect provide flats on
the pin intended to be received in a slotted fifth wheel of a
tractor unit having an antijackknife apparatus according to the
invention. It is to be noted that the coupling block of FIG. 13
simply allows such a trailer to be coupled to the tractor but would
not allow the anti-jackknife apparatus to be used since the
coupling block will be freely turnable on the coupling pin.
As can be seen from FIG. 13, the block is made in two halves 284,
286 which are coupled together by a hinge 288. The hinge allows the
two halves of the coupling block to be moved between open positions
such as those shown in the drawing, and positions in which the two
halves are closed together as indicated by arrow 290. The halves
are retained in the closed position by a spring member 292 on one
half which engages over a pin 294 on the other half.
The two halves 284, 286 are formed with opposing recesses 296, 298
which are shaped so that, when the halves 284, 286 are in the
closed position, the recesses together define an opening
complimentary to the shape of the coupling pin 282. Each recess
296, 298 has a lower portion 300, 302 which receives part of the
bottom flange of coupling pin 282. Accordingly, the two halves of
the coupling block can be closed around the coupling pin 282. The
portions 300, 302 of the respective recesses 296, 298 prevent the
coupling block being accidently pulled off the pin 282. The only
way the block can be removed is by releasing the spring element 292
and hinging apart the two halves 284, 286 of the block.
The halves of the block are shaped so that when they are in the
closed position, parallel flats 304, 308 are defined at
respectively opposite sides of the block. These flats are arranged
to fit closely into the slot in the relevant fifth wheel when the
trailer to which the block is fitted is to be coupled to a tractor
unit. The outer end of the block 286 defines an inclined face 310
which is engaged by the locking mechanism associated with the fifth
wheel (such as that indicated at 76 in FIG. 4). The shaping of face
310 is such that the block is positively and firmly locked into the
slot in the fifth wheel.
FIGS. 14 to 16 illustrate a modified fifth wheel assembly which
includes a device for locking a trailer coupled to the assembly
against turning with respect to the fifth wheel. This allows a
standard trailer having a round coupling pin to be operatively
coupled to the anti-jackknife apparatus. The embodiment of FIGS. 14
to 16 will be described as a modification of the embodiment of
FIGS. 1 to 6 although it is to be clearly understood that the
locking device of FIGS. 14 to 16 is applicable to any embodiment of
the invention in which a flat-sided coupling pin would otherwise be
required.
For convenience of description, primed reference numerals have been
used in FIGS. 14 to 16 to denote parts which correspond with parts
in FIGS. 1 to 6.
In FIGS. 14 and 15 the part circular portion of the fifth wheel 32'
of the anti-jackknife apparatus is visible at 34'. This portion is
formed with a parallel sided slot 38' to receive a coupling pin 312
which depends from a plate 314 secured to the underside of the
leading end portion of a trailer to be coupled to the
anti-jackknife apparatus. Plate 314 and pin 312 are conventional
fixtures on a standard trailer. Plate 314 differs from a standard
plate only in that it is provided with two apertures 316, the
purpose of which will be described later. In FIG. 15, plate 314 is
visible below part of the trailer body indicated at 318.
The part-circular portion 34' of the fifth wheel has a depending
skirt 62' which is coupled by bolts to the upper margin of a
cylindrical member 60' surrounding a plate 58'. Plate 58' together
with a cylindrical member 60' are turnably mounted on a tapered
shaft 50' attached to a base plate 42' which is in turn pivotally
coupled to the frame of the tractor unit.
In the space between the part-circular portion 34' of the fifth
wheel and the circular plate 58' is a cupshaped member 320 having a
cylindrical outer surface. Member 320 has a central aperture which
receives the upper end of shaft 50'. This end of the shaft is
screw-threaded and the cup member is retained by a nut 322 on the
shaft. It will be appreciated that the inner end of slot 38' is of
semi-circular shape and is centered on a vertical axis co-incident
with the common vertical axis of shaft 50' and cup member 320. It
will be noted that the upper end of member 320 is spaced below the
underside of the portion 34' of the fifth wheel to allow clearance
for the head of the coupling pin 312.
Cup member 320 acts as a guide for a vertically slidable collar 324
which has integral lateral projections 328 carrying vertical
locking pins 330. These pins can be projected upwardly through
corresponding apertures 332 in the part circular portion 34' of the
fifth wheel to engage in the respective apertures 316 in the
coupling pin plate 314 on the trailer and thereby lock the trailer
and the fifth wheel of the anti-jackknife apparatus against
relative turning movement. In FIG. 14, the locking pins 330 are
shown in retracted positions in which their upper ends are
substantially flush with the upper surface of the part circular
portion 34' of the fifth wheel. The pins are movable between these
positions and elevated locking positions indicated in chain line at
334 in which they engage in the apertures 316 in the trailer
coupling plate 314 (assuming the trailer is coupled to the fifth
wheel). It will of course be appreciated that in FIG. 14, the
trailer coupling pin 312 and plate 314 are shown in exploded
positions for clarity of illustration and that plate 314 will be in
contact with the upper surface of the part circular portion 34'
when the trailer is engaged with the fifth wheel.
Movement of the locking pins 330 between their retracted and
elevated positions is effected by a fork member 336 operable by a
control arm 338. Member 336 has side limbs 340 coupled to the
projections 328 of collar 324, and a central limb 342 pivotally
mounted between two lugs 344 on the circular plate 58'. The limbs
340 of member 336 are coupled to the projections 328 of collar 324
by laterally projecting pins 346 (only one of which is visible) on
the projections 328 of collar 324, which pins are received in slots
348 in the limbs. The control arm 338 projects to the rear of the
fifth wheel through a vertical slot 350 in skirt 62' (see FIG. 15)
and has a handle 352 at its outer end. It will be appreciated that
downward movement of the outer end of the arm 338 from the position
in which it is shown in FIG. 14 will cause collar 324 to lift the
locking pins 330 to the elevated positions in which they are shown
in FIG. 15 (in which only one pin is visible) and in which they are
indicated at 334 in FIG. 14.
Arm 338 is manually operable and is arranged to be locked in its
down position (with the pins 330 raised) by means of a pivoted
latch 354 (see particularly FIG. 16). Latch 354 is biassed by a
spring 356 into the upright position in which it is shown in FIG.
16 and is formed with a notch 358 in which the arm 338 engages.
Latch 354 is deflectable in the direction of arrow 360 in FIG. 16
against its spring biassing to allow the arm 338 to return to its
upper position and allow the pins 330 to retract under their own
weight.
It will be appreciated that the locking arrangement described above
allows a tractor unit fitted with an anti-jackknife apparatus
according to the invention to be coupled with a conventional
trailer with minimum modification of the trailer. It is simply
necessary for the apertures 316 to be formed in plate 314. This can
be readily effected with the plate 314 in place on the trailer, for
example, using a conventional cutting torch.
The preceding description applies to specific embodiments of the
invention only and it is of course to be understood that many
variations are possible within the broad scope of the invention.
For example, the description refers to several specific types of
braking means, but is not to be considered as exhaustive. Further,
although the brake actuators referred to in connection with the
preceding embodiments have been described as pneumatically
operated, hydraulically or electrically operated actuators may be
used with appropriate changes in their control. It is also to be
understood that the two slot form of fifth wheel shown in FIG. 7
could be used in the other embodiments in place of the single-slot
fifth wheels shown. Also, the control system described with
reference to FIG. 6 may be used in any of the embodiments which
employ a hydraulically or pneumatically operated braking
system.
It should finally be noted that the term "tractor-trailer" as used
in this application is intended to be construed broadly as
including any articulated vehicle. For example, the invention could
be used in articulated recreational vehicles. Also, the expression
"tractor unit" is to be interpreted as including any units from
which a trailer is towed. For example, in the trucking field, an
anti-jackknife apparatus according to the invention could be used
in association with a so-called "pup" trailer; that is, an
auxiliary trailer which is towed behind another trailer. A wheeled
sub-assembly or bogey (often referred to as a "Joe Boy") is
conventionally positioned below the leading end of the pup trailer
and is attached to the towing trailer by a rigid tow coupling. The
bogey carries a fifth wheel to which the pup trailer is coupled by
a coupling pin. An anti-jackknife apparatus according to the
invention could be provided in association with the fifth wheel of
the bogey. Accordingly, in the case of a tractor unit towing a
first trailer and also a pup trailer, two fifth wheels are
employed. Each of them may be provided with an anti-jackknife
apparatus according to the invention.
* * * * *